LCD touch screen of the prior art as is shown in FIG. 25 and FIG. 28 comprises the first underlayer 71a, the second underlayer 72a and liquid crystal imaging material 73a which is set between the first underlayer 71a and the second underlayer 72a. As is shown in FIG. 26, pixel electrodes 7231a which are used for controlling reversal of liquid crystal imaging material 73a are set on the said second underlayer 72a, and the said pixel electrodes 7231a are laid by matrix structure to form pixel electrode matrix 723a. Pixel electrode drive circuits 7232a are set around each pixel electrode 7231a. The said pixel electrode drive circuits 7232a are used for applying drive signals to a pixel electrode 7231a, so as to enable liquid crystal imaging material which is over against the pixel electrodes 7231a to be turned over by the pixel electrodes 7231a. Color filter 711a is set on the said first underlayer 71a. Two polaroids are respectively set at the respective outer side surfaces of the underlayer 71a and 72a. As a rule, the first underlayer 71a which is set with color filter 711a is served as the upper surface of the LCD, namely, the first underlayer 71a of the two underlayers is set at the side which is close to users. The second underlayer 72a which is set with pixel electrode matrix 723a is served as lower surface of the LCD, namely, the second underlayer 72a of the two underlayers is set at the side which is far away from users. Backlight of the LCD shall also be set under the said second underlayer 72a. The said pixel electrodes 7231a can be made of transparent conductive material, for instance Indium Tin Oxide which is ITO for short. Common potential electrode layer 76a providing common potential is also set inside of the said LCD. To ensure that there is low electrical resistively for the drive circuit, the said pixel electrode drive circuits 7232a are made of metal conductive material. To prevent users to see pixel electrode drive circuits 7232a on the said pixel electrode matrix 723a, black matrix 75a which is made of light proof and anti-glare material is also set on the said color filter 711a. As is shown in FIG. 27, black matrix 75a comprises masking tapes 751a, and all orthographic projections on the pixel electrode matrix 723a for the said masking tapes 751a fall on all pixel electrode drive circuits 7232a, thus, pixel electrode drive circuits 7232a are invisible by virtue of masking tapes 751a. Therefore, structure of the said black matrix 75a is related to the layout of the pixel electrode driving circuits 7232a. Because pixel electrode driving circuits 7232a are arranged at the void areas between various pixel electrodes 7231a, the said black matrix 75a form reticular structure constituted by masking tapes 751a. In FIG. 27, the dash area is the area where masking tapes 751a lie, for the purpose of stopping users to see pixel electrode driving circuits 7232a under black matrix 75a. The void part is enclosed by masking tapes 751a, so imaging for each pixel is displayed from the void part. Thus, images of all pixels inside of the LCD display area form a complete image. In both FIG. 25 and FIG. 28, black matrix 75a and color filter 711a are divided into two layers theoretically before being displayed. For actual products, color filter 711a can be set in the void area in the said black matrix 75a, thus black matrix 75a and color filter 711a are combined into one layer.
LCD of the prior art comprises twisted nematic LCD, which is TN LCD for short, as well as In-Plane Switching LCD, IPS LCD for short. To the invention, main distinctions between the two are that, for TN LCD as is shown in FIG. 25, the said common potential electrode layer 76a is set on the surface which is over against the pixel electrode matrix 723a, namely on the first underlayer 71a, the said common potential electrode layer 76a can be simply made into a conductive electrode plane with ITO material, electric field which is over against the electrode plates is established between the common potential electrode layer 76a and the various pixel electrodes 7231a of the pixel electrode matrix 723a; for IPS LCD as is shown in FIG. 28, the said common potential electrode layer 76a is set on the same plane with pixel electrode matrix 723a, namely on the second underlayer 72a, then, electrode plane for the said common potential electrode layer 76a shall be over against the void areas between various pixel electrodes 7231a, namely over against the various pixel electrode drive circuits 7232a, thus, the common potential electrode layer 76a is the common potential plate electrode which is made of ITO strip electrodes similar to reticular structure of black matrix 75a, and electric field which is adjacent to the plate electrode is established between the common potential electrode layer 76a and various pixel electrodes 7231a of the pixel electrode matrix 723a. 
For the scheme of the prior art combining capacitive touch sensor and display screen, a part of which is that overlap capacitive touch sensor at the outside of any type of touch screen. To enable the display screen to be thinner, fitted with LCD, the other part of the prior art is that the capacitive touch sensor is integrated on the LCD, namely LCD touch screen. The said touch LCD has already become the future development tendency. An approach for the integration of LCD with touch sensor is that touch sensor is made on the first underlayer of the LCD, one of the structure is that set the whole touch sensor on the first underlayer 71a, which in material is the method of stacking at the outside of the display screen; the other structure is that set plate electrode at both sides of the first underlayer 71a taking the first underlayer 71a as the insulating medium. Because all first underlayers 71a for the LCD are required to reach the effect of thin display screen after thinning process, while thinning process fails to be reached after touch sensor is integrated, thus, the touch LCD with such integration method fails to reach the effect of thin display screen, even if the thin type display screen effect can be realized, high manufacturing cost shall be paid, which is unfit for volume production. Approach for the integration of LCD with touch sensor for the other kind of LCD is that set the touch sensor in the LCD. Without prejudice to the image of LCD screen, touch sensor of the said existing technology is totally made of transparent conductive material such as ITO material. To avoid high resistivity caused by too close distance between the two layers of electrodes made of transparent conductive material, thus affecting effect of sensing, single layer capacitive touch sensors structure can't be used in the touch sensor, while the adoption of two layers of capacitive sensor structure requires certain distance maintained by two layers of electrodes. One structure is set touch sensor into the LCD as a whole. Because space shall be maintained between the two layers of electrodes, thickness of the LCD will be increased, failing to conform to the development tendency of the LCD to thin even ultra-thin ones. Another structure is that two layers of electrodes are respectively set at both sides of the liquid crystal imaging material 73a, then, one layer of electrodes must be set on the second underlayer 72a which is already set with pixel electrode matrix 723a. Since very sophisticated technological level is required for the pixel electrodes 7231a and pixel electrode drive circuits 7232a which are set on the second underlayer 72a (intensive and arranged as matrix), a layer of touch sensor electrodes processed thereupon will impose more strict process requirement, thus, low processing yield is easily to be caused, which has greatly increased the manufacturing cost for the LCD.
To sum up, there is no solution which can meet the thin touch LCD tendency under the condition of low cost and no increase of process requirements.